Computing for Space Science – Current practice and future challenges

Peter Allan

Head, Space Data Division

Overview

• Brief overview of work of SSTD

• Software, data, archives

• Systems in space

• Challenges for the future

Work of SSTD

• Astronomy and Earth Observation• Design studies• Design, build and test instruments• Launch instruments (e.g GERB on Wednesday)• Science Operations• Communicate with spacecraft• Develop data processing systems• Process, archive and disseminate data• Long term data curation• Telescope pointing

GERB

Internal black-body

Front End Electronics

Scan Mirror

Telescope

Calibration Monitor

Quartz Filter

Earth View

Fold mirror and detector

18g

Launches

RAL Ground Station

• RAL antennae 12m plus 2.4m• Chilbolton 25m• Jodrell Bank 76m• NASA DSN

– several hundred 10m-class antennae ?

Ground Stations

• Equipment controlled by standard PC

• Standard protocols are the key– Developed by CCSDS

• Like IP, but tuned for use in space– Must handle long round trip

times (many mins to hours)– Must handle disjoint

connections– Power is always at a premium

Science Operations

Operations on Cluster

Double Star

Mars Express

General Computing

• Windows and Linux on desktop– A few Sun and HP workstations

• Linux, Solaris and Tru64 on science servers

• Windows servers for office system and technical tools (e.g. CAD)

Data Centres and Archives

• British Atmospheric Data Centre

• NERC Earth Observation Data Centre

• Cluster/Doublestar

• UK Solar System Data Centre– Solar data– Data on Ionosphere– Space plasma data

Software Engineering

• ISO 9001• Apply the “appropriate level” of rigour• Use appropriate methods

– Iterative development– Science code industrial strength app– Develop formal requirements

• Workshops on improving processes– Use of standard tools?– Departmental CVS repository?

Operating Systems for Space

• Operating systems for space– H/W is previous generation– No disk drives– Tapes replaced with solid state memory– Still use assembler for some applications– Starting to use unix-like systems– Web server in space

Data Analysis and Visualisation

• Languages– Fortran, C, C+

+, Java, Perl, Python

• IDL– ENVI

Data Processing and Analysis

• Starlink

• GGSPS

• AstroGrid

• NERC data grid

Starlink

• Software for processing astronomical data for nearly all wavelengths

• Integrated data processing tools

• Library for writing new tools

• Uniform data format• Fortran (+C) Java• Lasted for 26 years

GGSPS

• GERB Ground Segment Processing System

• Multi-national data processing system– Germany RAL Belgium RAL Users

• Written in C++ (mostly not OO)

256

dete

ctor

pix

els

282 steps

Satellite rotation period = 0.6 s

282 steps for full Earth disc = 169.2 s

Between each Earth scan, internal BB measurement taken for calibration

At correct viewing geometry, calibration monitor records scattered solar light as a relative measure over time

Average three scans in each channel to improve S/N

Total repeat time = 169.2*6 ~ 15 min.

2 channels: Total Total+quartz filter (SW)

Future Challenges

• Autonomy

– Rovers on Mars

– On board analysis of satellite imagery

• Interplanetary Internet

• Integrating Grid computing into daily work

Interplanetary Internet

• Spread communications infrastructure throughout solar system

• E-mail rover1@syria-plenum.mars.sol

• Need the right protocols– Long round trip times!

Grid Computing

• AstroGrid

• NERC Data Grid

• Both about improving access to data– Search, merge, analyse

• Hooked into international data sources– IVOA

Grid Computing

• Examples from AstroGrid

– Improving access to data

– “What if” questions answered in minutes, not months

– Enabling rapid response to sudden bursts

Optical Data Archive X-ray Data Archive

Processing Pipeline

Astronomy from the Desktop

multi- views of a Supernova Remnant

Shocks seen in the X-ray

Heavy elementsseen in the optical

Dust seen in the IR

Relativistic electrons seen in the radio

Needles in a haystack Hambly et al 2001

- faint moving object is a cool white dwarf- may be solution to the dark matter problem- but hard to find : one in a million- even harder across multiple archives

yesterday

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Registry Workflow

GLUE Certification VO Space

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Image from

E

SO

Image + IRIS data

Gamma Ray BurstsGamma Ray Bursts

D. Ducros, ESAReprocessing of ionospheric STP datachange coords from earth to celestial

Collate data frommultiple telescopesover months - meta data issues

Localise GRB alertin minutes – as faderapidly.

SWIFT satelliteobserves gammaray burst

Compare against SNlight curves – bump shows eveidence for a SN in the GRB(Price et al, 2002)

Interaction with observatory pipe-lines

Cross reference multi-λdata – ID pre-cursorand or environment

Large computationalphotometric redshift calcs on multi-λ > gives distance

Questions ?

yesterday

browserfrontend

CGIrequest

html

web page

DBengine

SQL

data

today

appl

icat

ion

webservice

SOAP/XML request

SOAP/XML data

DBengine

SQL

nativedata

anyt

hin

g

standard formats

tomorrow

appl

icat

ion

webservice

job

results

anyt

hin

g

webservice

webservice

webservice

webservice

webservice

Registry Workflow

GLUE Certification VO Space

standard semantics

publish W

SDL

gri

d c

onn

ect

ed